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Re: [PATCH v7 17/17] spapr: Fold spapr_node0_size() into its only caller
From: |
David Gibson |
Subject: |
Re: [PATCH v7 17/17] spapr: Fold spapr_node0_size() into its only caller |
Date: |
Wed, 4 Mar 2020 12:25:55 +1100 |
On Tue, Mar 03, 2020 at 11:32:49AM +0100, Greg Kurz wrote:
> On Tue, 3 Mar 2020 14:43:51 +1100
> David Gibson <address@hidden> wrote:
>
> > The Real Mode Area (RMA) needs to fit within the NUMA node owning memory
> > at address 0. That's usually node 0, but can be a later one if there are
> > some nodes which have no memory (only CPUs).
> >
> > This is currently handled by the spapr_node0_size() helper. It has only
> > one caller, so there's not a lot of point splitting it out. It's also
> > extremely easy to misread the code as clamping to the size of the smallest
> > node rather than the first node with any memory.
> >
> > So, fold it into the caller, and add some commentary to make it a bit
> > clearer exactly what it's doing.
> >
> > Signed-off-by: David Gibson <address@hidden>
> > ---
> > hw/ppc/spapr.c | 37 +++++++++++++++++++++----------------
> > 1 file changed, 21 insertions(+), 16 deletions(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 2eb0d8f70d..d674a9f48f 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -296,20 +296,6 @@ static void
> > spapr_populate_pa_features(SpaprMachineState *spapr,
> > _FDT((fdt_setprop(fdt, offset, "ibm,pa-features", pa_features,
> > pa_size)));
> > }
> >
> > -static hwaddr spapr_node0_size(MachineState *machine)
> > -{
> > - if (machine->numa_state->num_nodes) {
> > - int i;
> > - for (i = 0; i < machine->numa_state->num_nodes; ++i) {
> > - if (machine->numa_state->nodes[i].node_mem) {
> > - return
> > MIN(pow2floor(machine->numa_state->nodes[i].node_mem),
> > - machine->ram_size);
> > - }
> > - }
> > - }
> > - return machine->ram_size;
> > -}
> > -
> > static void add_str(GString *s, const gchar *s1)
> > {
> > g_string_append_len(s, s1, strlen(s1) + 1);
> > @@ -2653,10 +2639,24 @@ static hwaddr spapr_rma_size(SpaprMachineState
> > *spapr, Error **errp)
> > MachineState *machine = MACHINE(spapr);
> > SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
> > hwaddr rma_size = machine->ram_size;
> > - hwaddr node0_size = spapr_node0_size(machine);
> >
> > /* RMA has to fit in the first NUMA node */
> > - rma_size = MIN(rma_size, node0_size);
> > + if (machine->numa_state->num_nodes) {
> > + /*
> > + * It's possible for there to be some zero-memory nodes first
> > + * in the list. We need the RMA to fit inside the memory of
> > + * the first node which actually has some memory.
> > + */
> > + int i;
> > +
> > + for (i = 0; i < machine->numa_state->num_nodes; ++i) {
> > + if (machine->numa_state->nodes[i].node_mem != 0) {
> > + rma_size = MIN(rma_size,
> > + machine->numa_state->nodes[i].node_mem);
> > + break;
> > + }
> > + }
> > + }
> >
> > /*
> > * VRMA access is via a special 1TiB SLB mapping, so the RMA can
> > @@ -2673,6 +2673,11 @@ static hwaddr spapr_rma_size(SpaprMachineState
> > *spapr, Error **errp)
> > rma_size = MIN(rma_size, smc->rma_limit);
> > }
> >
> > + /*
> > + * RMA size must be a power of 2
> > + */
> > + rma_size = pow2floor(rma_size);
> > +
>
> I saw somewhere else that the reason behind this might be
> related to:
>
> https://git.qemu.org/?p=qemu.git;a=commitdiff;h=6010818c30ce9c
>
> commit 6010818c30ce9c796b4e22fd261fc6fea1cecbfc
> Author: Alexey Kardashevskiy <address@hidden>
> Date: Thu Jul 3 13:10:05 2014 +1000
>
> spapr: Split memory nodes to power-of-two blocks
>
> Is this the reason ?
Quite likely.
> In any case, it would probably help to mention somewhere
> why the rounding is introduced by this patch.
Drat. I meant to sort out your comment on the last spin better than
this, but got part way through and forgot what I was doing.
I'm going to merge everything except this last patch into ppc-for-5.0
now, and try to sort out this one a bit later.
>
> > if (rma_size < MIN_RMA_SLOF) {
> > error_setg(errp,
> > "pSeries SLOF firmware requires >= %ldMiB guest RMA (Real Mode Area
> > memory)",
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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- [PATCH v7 12/17] spapr: Don't use weird units for MIN_RMA_SLOF, (continued)
- [PATCH v7 12/17] spapr: Don't use weird units for MIN_RMA_SLOF, David Gibson, 2020/03/02
- [PATCH v7 08/17] target/ppc: Streamline calculation of RMA limit from LPCR[RMLS], David Gibson, 2020/03/02
- [PATCH v7 10/17] target/ppc: Only calculate RMLS derived RMA limit on demand, David Gibson, 2020/03/02
- [PATCH v7 17/17] spapr: Fold spapr_node0_size() into its only caller, David Gibson, 2020/03/02
- [PATCH v7 07/17] target/ppc: Use class fields to simplify LPCR masking, David Gibson, 2020/03/02
- [PATCH v7 09/17] target/ppc: Correct RMLS table, David Gibson, 2020/03/02
- [PATCH v7 15/17] spapr: Don't clamp RMA to 16GiB on new machine types, David Gibson, 2020/03/02
- [PATCH v7 13/17] spapr,ppc: Simplify signature of kvmppc_rma_size(), David Gibson, 2020/03/02